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Sunday, January 22, 2006

Sydney's water crisis - its our problem too.

Robertson is critical to Sydney's water supply.
This image of the region between Robertson and Sydney, and west to the Blue Mountains, (adapted from "Google Earth"), amounts to a photo of the main Sydney Water Catchment area - and that is what I wish to talk about, today. (Double click for a larger view).

The Blue Mountains area mostly drains into the Warragamba Dam, the main dam supplying water for Sydney. Sydney people, especially the ABC 702 radio presenters, prattle on endlessly about rain "not falling in the catchment". They mean the "Blue Mountains". But that is just part of the story.

As I mentioned yesterday, Robertson is in a very high rainfall area. From 1962 onwards the mean annual rainfall has been 1616 mm (or 63.6 inches). By contrast, Canberra (my old home town) receives about 22 inches, each year.

Caalang Creek, rises in Robertson, and flows south and west, because of the high volcanic ridges just north and east of the town, notably on Trig Station Lane (in East Kangaloon) and Mackey's Lane. These ridges act as a local "divide" to send the main creek which collects most of the precious rain which falls in Robertson out into the Wingecarribee River, and hence west, and eventually into the great Warragamba Dam


Not everybody (even amongst the local Robertson residents) seems to realise that our little Caalang Creek is the absolute starting point of the Wingecarribee River, a major tributory of the river system feeding Warragamba Dam. The Wollondilly River, drains a much larger, but drier, area, from Goulburn northwards. By contrast, the Wingecarribee River has a consistently good flow of water, starting from right here in Caalang Creek, in Robertson.

That is just part of the story. Just over the hill, past the Robertson Showgrounds, where the sign says "East Kangaloon" is the very headwaters of the Upper Nepean River. That river flows directly into the Nepean Dam, another of the dams used to supply Sydney with water. Similarly, the areas beyond the Showgrounds, in Lemons Road, and further east, at the end of Mackey's Lane also drain into the Upper Nepean River.

But wait, there's more! At the top end of Hoddle Street, behind the Old Cheese Factory, starts a little creek which becomes Barrengarry Creek, which makes Belmore Falls

so spectacular.

Similarly, rain which falls at my place, on Missingham Parade, or up along the Illawarra Highway, around Pearsons Lane, also flows into Barrengarry Creek.

All that water flows down into the Kangaroo Valley, where it is trapped in the Tallawa Dam. It is used to supply not only the locals, and the people in Nowra, but also, some water is pumped back up to the Fitzroy Falls Reservoir, and thence by way of a tunnel under Burrawang, into Wingecarribee Reservoir. From there, water is released downstream into Warragamba Dam. Sometimes water is diverted through the Glen Quarry Cut, into the Upper Nepean River, and on to the Nepean Dam, where it is also used for Sydney's water supply.

That is a very circuitous, and artificial, route for even more of the water which starts as rainfall in Robertson to end up in Sydney.

So Robertson is critical to Sydney's water supply.


Once our rainfall turns into river flows, it gets trapped for use in Sydney. However, at that point Sydney wastes much of this precious water.


The only Robertson rain which escapes being used (or wasted) in Sydney is that which falls on the south and eastern sections of Mackey's Lane. That rain water drains down into the Macquarie Rivulet, just behind the Pie Shop. and down over Macquarie Pass, and into Lake Illawarra.

Warragamba Dam is currently at about 40% full. Partly this is a result of the prolongued drought (which has not ended yet, despite recent good rains). However, with water usage, there is always the question: is the water being used well?

Readers are invited to check out the information on Sydney's water usage and storage crisis, at the following site: "I live in", from which this graph of Warragamba Dam water levels was sourced.


Sydney is using just about every drop of water which it can get hold of. And it wants more water!

There is high-level talk about creating drinking water by desalination of Sea Water, at Kurnell. That is an extremely expensive proposal. Surely Sydney could use its existing water resources more wisely? How much water is wasted in continuously flushing urinals in mens' toilets in public building all over the city? What about water saving devices in every shower in every house and hotel in Sydney? What about industry recycling its own water? What about all that water which falls in the city itself (not in the catchment) - how little of that is trapped by private water tanks? Country people do that as a matter of course!

It is time for Sydney to have a massive re-think of its entire water policy.


Anonymous said...

I couldn't agree more. My family has become OBSESSIVE about saving water - we invested in a rainwater tank (my country mum thinks it's a shame that with all the pollution we can't drink it) and the garden is full of buckets and barrels to catch the extra bits we might miss otherwise.
I think I can safely say that NOBODY I know thinks that a desalination plant is a good idea. As for IMPORTING WATER BY SHIP, have you ever heard the like? Local councils ought to encourage people to save water by helping them to have water tanks installed (this goes for every house in Australia) - we paid, if I might be excused the expression, a bucketload for ours and this apparently did not entitle us to having it installed in a place that the gutters would actually drain into!

Denis Wilson said...

Hi Anonymous.
Good to have a true believer on board.
Desalination is a nonsense - it might be justifiable (and affordable) in the Gulf States. But NOT here. Not when we are still allowing water to run straight down drains in public toilets; and with no re-use of grey water for football fields, etc.

Shame about your water tank not being positioned well.
I do not have mine yet, but when I do, it will probably get used for the garden, because I doubt I can afford a pump to use it inside the house. However, I am being as careful as I can about not wasting the water I do use.

I had not heard of the water-shipping plans. Reminds me of the idea which was around a few years ago, of dragging icebergs up from the Antarctic. That was before they realised the ice caps are melting too fast anyway!

Thanks for your views.